TY - JOUR
AU - Guan, Yafeng
AB - A colorimetric filtration method has been developed for the highly selective and sensitive determination of Ni2+ and Pb2+ ions. Determinations of Ni2+ and Pb2+ follow the filtration using nioxime (1,2-cyclohexanedione dioxime) and rhodizonic acid disodium salt, respectively, as colorimetric reagents. Different from regular instrumentation techniques, the metal chelate precipitations are continuously pumped into a home-made flow cell at a constant flow rate, and filtered by a cellulose acetate/nitrate membrane. The color changes of the membrane are imaged using a conventional flatbed scanner, and digitized. The special selection of individual channels in the red, green, and blue channels of the images filters the influences of coexisting ions and provides a highly selective detection of Ni2+ and Pb2+ cations. The linear relationship between the colorimetric response of the chosen channel and Ni2+ or Pb2+ concentrations indicates a quantitative detection. The detection limit for Pb2+ is 3 μM (almost half of the Chinese wastewater discharge standard concentration), and is well below the nM level (94 nM) for Ni2+ (a quarter of the WHO drinking water safe-exposure standard for Ni2+). The determinations take five to ten minutes. No shelf life issue exists because the chelating indicators react with metal directly without any pre-immobilizations.
TI - Colorimetric filtrations of metal chelate precipitations for the quantitative determination of nickel(ii) and lead(ii)
JO - The Analyst
DO - 10.1039/c1an15290d
DA - 2011-09-26
UR - https://www.deepdyve.com/lp/royal-society-of-chemistry/colorimetric-filtrations-of-metal-chelate-precipitations-for-the-Yqf68WqmtM
SP - 4197
EP - 4203
VL - 136
IS - 20
DP - DeepDyve
ER -